In fact, Musk seemed pleasantly surprised that the capsule performed as well as it did, delivering what he called a near-perfect "grand slam."

"When you've been deeply involved with the design of a complex machine, you know all the things that can go wrong," Musk said.

"So when you see it actually work, you're sort of surprised—which is not to say that we didn't expect it to work. It's just that you see so many ways that it could fail, and then it works, and you're just like, Wow."

The craft then spent several days in orbit performing a series of tests and demonstrations designed to prove that it could safely fulfill a $1.6-billion NASA contract to ferry cargo—and maybe astronauts—to the space station.

The highlight of the mission was Dragon's docking with the ISS on May 25, which marked the first time a commercial craft had made contact with the orbiting laboratory.

Mission managers encountered only one minor problem with the craft's laser guidance system, or LIDAR, just before Dragon was plucked from orbit by the space station's a robotic arm.

"We did have some slight trouble with the LIDAR ... but we were able to make some adjustments ... and so we're able to eliminate the LIDAR as a concern in the future," Musk said.

From start to finish, Dragon's return to Earth took about six hours, beginning at 5:49 a.m. ET Thursday. Once undocked from the station, the robotic arm released the capsule, allowing Dragon to reinsert itself into Earth orbit.

Approximately five hours later, the capsule's Draco thrusters fired for approximately ten minutes to reduce velocity by about 200 miles (320 kilometers) an hour—just enough for it to drop out of orbit and begin its fall back to Earth.

A few minutes later, Dragon jettisoned its trunk section, which included its solar panels, and deployed its three parachutes.

When the parachutes opened and "Dragon was descending normally, that's the point at which I felt relieved and knew that the mission was likely to be 100-percent successful," Musk said.

"Not Much to Fix"

Alan Lindenmoyer, manager of NASA's commercial crew and cargo program, said at the press conference that he expects SpaceX will soon be given final approval for routine cargo transport to the ISS.

"I don't think it's going to take very long for us to make the determination that this was an extremely successful mission," Lindenmoyer said.

In the coming months SpaceX will focus its efforts on an upgraded version of Dragon that will be fit to carry astronauts, CEO Musk said. (Related: Will SpaceX also send humans to Mars?)

Engineers are also working on a system that will allow the craft to land on solid ground with helicopter-like precision.

Other than that, Musk doesn't anticipate any major changes to Dragon's design.

"We'll make minor adjustments and probably improve a little more of the automation, so we don't have to have quite so many people in mission control," he said.